JDBC 05: 插入,修改和删除数据

1.　　插入一个新用户

public static void insert(String username,String password) {

        Connection con = null;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        
        try {
            con = JDBCUtils.getConnection();
            
            String sql = "insert into user(username,password) values(?,?)";
            stmt = con.prepareStatement(sql);
            stmt.setString(1, username);
            stmt.setString(2, password);
            int result = stmt.executeUpdate(); // 返回值代表收到影响的行数
            
        } catch (Exception e) {
            
            e.printStackTrace();
        } finally {
            JDBCUtils.close(rs, stmt, con);
        }
    }

2.　　修改用户的密码

public static void update(int id,String newPassword) {

        Connection con = null;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        
        try {
            con = JDBCUtils.getConnection();
            
            String sql = "update user set password = ? where id = ?";
            stmt = con.prepareStatement(sql);
            stmt.setString(1, newPassword);
            stmt.setInt(2,id);
        
            int result = stmt.executeUpdate(); 
            if(result > 0) {
                System.out.println("修改成功");
            }else {
                System.out.println("修改失败");
            }
            
        } catch (Exception e) {        
            e.printStackTrace();
        } finally {
            JDBCUtils.close(rs, stmt, con);
        }
    }

3.　　删除用户

public static void delete(int id) {

        Connection con = null;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        
        try {
            con = JDBCUtils.getConnection();
            
            String sql = "delete from user where id=?";
            stmt = con.prepareStatement(sql);
            stmt.setInt(1, id);
        
            int result = stmt.executeUpdate(); 
            if(result > 0) {
                System.out.println("删除成功");
            }else {
                System.out.println("删除失败");
            }
            
        } catch (Exception e) {
            
            e.printStackTrace();
        } finally {
            JDBCUtils.close(rs, stmt, con);
        }
    }